Complete public brief locale switching

frontend/app/methodology/[slug]/page.tsx

@@ -1,16 +1,37 @@
 import type { Metadata } from "next";
+import { cookies, headers } from "next/headers";
 import { notFound } from "next/navigation";
 import { MethodologyDetailPageView } from "@/components/public-content/PublicContentPages";
+import {
+  LANDING_LOCALE_COOKIE,
+  LANDING_LOCALE_QUERY_PARAM,
+  pickLandingLocale,
+  type LandingLocale,
+} from "@/components/landing/landingLocale";
 import {
   METHODOLOGY_PAGES,
   absolutePublicUrl,
   getMethodologyPage,
+  localizeMethodologyPage,
   methodologyPath,
 } from "@/content/public-content";
 
 type MethodologyPageParams = {
   slug: string;
 };
+type MethodologySearchParams = Promise<Record<string, string | string[] | undefined>>;
+
+async function resolvePublicContentLocale(searchParams: MethodologySearchParams): Promise<LandingLocale> {
+  const params = await searchParams;
+  const rawLocale = params[LANDING_LOCALE_QUERY_PARAM];
+  const queryLocale = Array.isArray(rawLocale) ? rawLocale[0] : rawLocale;
+  const [cookieStore, headerStore] = await Promise.all([cookies(), headers()]);
+  return pickLandingLocale(
+    queryLocale,
+    cookieStore.get(LANDING_LOCALE_COOKIE)?.value,
+    headerStore.get("accept-language"),
+  );
+}
 
 export function generateStaticParams() {
   return METHODOLOGY_PAGES.map((page) => ({ slug: page.slug }));
@@ -18,10 +39,15 @@ export function generateStaticParams() {
 
 export async function generateMetadata({
   params,
+  searchParams,
 }: {
   params: Promise<MethodologyPageParams>;
+  searchParams: MethodologySearchParams;
 }): Promise<Metadata> {
-  const { slug } = await params;
+  const [{ slug }, locale] = await Promise.all([
+    params,
+    resolvePublicContentLocale(searchParams),
+  ]);
   const page = getMethodologyPage(slug);
 
   if (!page) {
@@ -29,17 +55,18 @@ export async function generateMetadata({
       title: "Methodology not found",
     };
   }
+  const localizedPage = localizeMethodologyPage(page, locale);
 
   return {
-    title: page.title,
-    description: page.description,
+    title: localizedPage.title,
+    description: localizedPage.description,
     alternates: {
       canonical: methodologyPath(page),
     },
     openGraph: {
       type: "article",
-      title: page.title,
-      description: page.description,
+      title: localizedPage.title,
+      description: localizedPage.description,
       url: methodologyPath(page),
       modifiedTime: page.updatedAt,
     },
@@ -48,22 +75,28 @@ export async function generateMetadata({
 
 export default async function MethodologyDetailPage({
   params,
+  searchParams,
 }: {
   params: Promise<MethodologyPageParams>;
+  searchParams: MethodologySearchParams;
 }) {
-  const { slug } = await params;
+  const [{ slug }, locale] = await Promise.all([
+    params,
+    resolvePublicContentLocale(searchParams),
+  ]);
   const page = getMethodologyPage(slug);
 
   if (!page) {
     notFound();
   }
 
+  const localizedPage = localizeMethodologyPage(page, locale);
   const pathname = methodologyPath(page);
   const jsonLd = {
     "@context": "https://schema.org",
     "@type": "TechArticle",
-    headline: page.title,
-    description: page.description,
+    headline: localizedPage.title,
+    description: localizedPage.description,
     dateModified: page.updatedAt,
     mainEntityOfPage: absolutePublicUrl(pathname),
     author: {
@@ -79,7 +112,7 @@ export default async function MethodologyDetailPage({
         type="application/ld+json"
         dangerouslySetInnerHTML={{ __html: JSON.stringify(jsonLd) }}
       />
-      <MethodologyDetailPageView page={page} />
+      <MethodologyDetailPageView page={page} locale={locale} />
     </>
   );
 }

frontend/app/methodology/page.tsx

@@ -1,21 +1,54 @@
 import type { Metadata } from "next";
+import { cookies, headers } from "next/headers";
 import { MethodologyIndexPageView } from "@/components/public-content/PublicContentPages";
+import {
+  LANDING_LOCALE_COOKIE,
+  LANDING_LOCALE_QUERY_PARAM,
+  pickLandingLocale,
+  type LandingLocale,
+} from "@/components/landing/landingLocale";
+import { PUBLIC_CONTENT_COPY } from "@/content/public-content";
 
-export const metadata: Metadata = {
-  title: "Methodology",
-  description:
-    "PolyWeather public methodology for DEB forecast blending, settlement-source priority, freshness, and market weather analysis.",
-  alternates: {
-    canonical: "/methodology",
-  },
-  openGraph: {
-    title: "Methodology | PolyWeather",
-    description:
-      "Public methodology for DEB forecast blending, settlement-source priority, freshness, and market weather analysis.",
-    url: "/methodology",
-  },
-};
+type MethodologySearchParams = Promise<Record<string, string | string[] | undefined>>;
 
-export default function MethodologyPage() {
-  return <MethodologyIndexPageView />;
+async function resolvePublicContentLocale(searchParams: MethodologySearchParams): Promise<LandingLocale> {
+  const params = await searchParams;
+  const rawLocale = params[LANDING_LOCALE_QUERY_PARAM];
+  const queryLocale = Array.isArray(rawLocale) ? rawLocale[0] : rawLocale;
+  const [cookieStore, headerStore] = await Promise.all([cookies(), headers()]);
+  return pickLandingLocale(
+    queryLocale,
+    cookieStore.get(LANDING_LOCALE_COOKIE)?.value,
+    headerStore.get("accept-language"),
+  );
+}
+
+export async function generateMetadata({
+  searchParams,
+}: {
+  searchParams: MethodologySearchParams;
+}): Promise<Metadata> {
+  const locale = await resolvePublicContentLocale(searchParams);
+  const copy = PUBLIC_CONTENT_COPY[locale];
+  return {
+    title: copy.methodologyIndexEyebrow,
+    description: copy.methodologyIndexDescription,
+    alternates: {
+      canonical: "/methodology",
+    },
+    openGraph: {
+      title: `${copy.methodologyIndexEyebrow} | PolyWeather`,
+      description: copy.methodologyIndexDescription,
+      url: "/methodology",
+    },
+  };
+}
+
+export default async function MethodologyPage({
+  searchParams,
+}: {
+  searchParams: MethodologySearchParams;
+}) {
+  const locale = await resolvePublicContentLocale(searchParams);
+  return <MethodologyIndexPageView locale={locale} />;
 }

frontend/app/sources/[slug]/page.tsx

@@ -1,16 +1,37 @@
 import type { Metadata } from "next";
+import { cookies, headers } from "next/headers";
 import { notFound } from "next/navigation";
 import { SourceDetailPageView } from "@/components/public-content/PublicContentPages";
+import {
+  LANDING_LOCALE_COOKIE,
+  LANDING_LOCALE_QUERY_PARAM,
+  pickLandingLocale,
+  type LandingLocale,
+} from "@/components/landing/landingLocale";
 import {
   SOURCE_PAGES,
   absolutePublicUrl,
   getSourcePage,
+  localizeSourcePage,
   sourcePath,
 } from "@/content/public-content";
 
 type SourcePageParams = {
   slug: string;
 };
+type SourceSearchParams = Promise<Record<string, string | string[] | undefined>>;
+
+async function resolvePublicContentLocale(searchParams: SourceSearchParams): Promise<LandingLocale> {
+  const params = await searchParams;
+  const rawLocale = params[LANDING_LOCALE_QUERY_PARAM];
+  const queryLocale = Array.isArray(rawLocale) ? rawLocale[0] : rawLocale;
+  const [cookieStore, headerStore] = await Promise.all([cookies(), headers()]);
+  return pickLandingLocale(
+    queryLocale,
+    cookieStore.get(LANDING_LOCALE_COOKIE)?.value,
+    headerStore.get("accept-language"),
+  );
+}
 
 export function generateStaticParams() {
   return SOURCE_PAGES.map((source) => ({ slug: source.slug }));
@@ -18,10 +39,15 @@ export function generateStaticParams() {
 
 export async function generateMetadata({
   params,
+  searchParams,
 }: {
   params: Promise<SourcePageParams>;
+  searchParams: SourceSearchParams;
 }): Promise<Metadata> {
-  const { slug } = await params;
+  const [{ slug }, locale] = await Promise.all([
+    params,
+    resolvePublicContentLocale(searchParams),
+  ]);
   const source = getSourcePage(slug);
 
   if (!source) {
@@ -29,17 +55,18 @@ export async function generateMetadata({
       title: "Source not found",
     };
   }
+  const localizedSource = localizeSourcePage(source, locale);
 
   return {
-    title: source.title,
-    description: source.description,
+    title: localizedSource.title,
+    description: localizedSource.description,
     alternates: {
       canonical: sourcePath(source),
     },
     openGraph: {
       type: "article",
-      title: source.title,
-      description: source.description,
+      title: localizedSource.title,
+      description: localizedSource.description,
       url: sourcePath(source),
       modifiedTime: source.updatedAt,
     },
@@ -48,22 +75,28 @@ export async function generateMetadata({
 
 export default async function SourceDetailPage({
   params,
+  searchParams,
 }: {
   params: Promise<SourcePageParams>;
+  searchParams: SourceSearchParams;
 }) {
-  const { slug } = await params;
+  const [{ slug }, locale] = await Promise.all([
+    params,
+    resolvePublicContentLocale(searchParams),
+  ]);
   const source = getSourcePage(slug);
 
   if (!source) {
     notFound();
   }
 
+  const localizedSource = localizeSourcePage(source, locale);
   const pathname = sourcePath(source);
   const jsonLd = {
     "@context": "https://schema.org",
     "@type": "Dataset",
-    name: source.title,
-    description: source.description,
+    name: localizedSource.title,
+    description: localizedSource.description,
     url: absolutePublicUrl(pathname),
     dateModified: source.updatedAt,
     creator: {
@@ -83,7 +116,7 @@ export default async function SourceDetailPage({
         type="application/ld+json"
         dangerouslySetInnerHTML={{ __html: JSON.stringify(jsonLd) }}
       />
-      <SourceDetailPageView source={source} />
+      <SourceDetailPageView source={source} locale={locale} />
     </>
   );
 }

frontend/app/sources/page.tsx

@@ -1,21 +1,54 @@
 import type { Metadata } from "next";
+import { cookies, headers } from "next/headers";
 import { SourcesIndexPageView } from "@/components/public-content/PublicContentPages";
+import {
+  LANDING_LOCALE_COOKIE,
+  LANDING_LOCALE_QUERY_PARAM,
+  pickLandingLocale,
+  type LandingLocale,
+} from "@/components/landing/landingLocale";
+import { PUBLIC_CONTENT_COPY } from "@/content/public-content";
 
-export const metadata: Metadata = {
-  title: "Weather Sources",
-  description:
-    "PolyWeather public source notes for MGM, METAR, HKO, NOAA, ECMWF, and settlement-source weather analysis.",
-  alternates: {
-    canonical: "/sources",
-  },
-  openGraph: {
-    title: "Weather Sources | PolyWeather",
-    description:
-      "Public source notes for MGM, METAR, HKO, NOAA, ECMWF, and settlement-source weather analysis.",
-    url: "/sources",
-  },
-};
+type SourcesSearchParams = Promise<Record<string, string | string[] | undefined>>;
 
-export default function SourcesPage() {
-  return <SourcesIndexPageView />;
+async function resolvePublicContentLocale(searchParams: SourcesSearchParams): Promise<LandingLocale> {
+  const params = await searchParams;
+  const rawLocale = params[LANDING_LOCALE_QUERY_PARAM];
+  const queryLocale = Array.isArray(rawLocale) ? rawLocale[0] : rawLocale;
+  const [cookieStore, headerStore] = await Promise.all([cookies(), headers()]);
+  return pickLandingLocale(
+    queryLocale,
+    cookieStore.get(LANDING_LOCALE_COOKIE)?.value,
+    headerStore.get("accept-language"),
+  );
+}
+
+export async function generateMetadata({
+  searchParams,
+}: {
+  searchParams: SourcesSearchParams;
+}): Promise<Metadata> {
+  const locale = await resolvePublicContentLocale(searchParams);
+  const copy = PUBLIC_CONTENT_COPY[locale];
+  return {
+    title: copy.sourceIndexEyebrow,
+    description: copy.sourceIndexDescription,
+    alternates: {
+      canonical: "/sources",
+    },
+    openGraph: {
+      title: `${copy.sourceIndexEyebrow} | PolyWeather`,
+      description: copy.sourceIndexDescription,
+      url: "/sources",
+    },
+  };
+}
+
+export default async function SourcesPage({
+  searchParams,
+}: {
+  searchParams: SourcesSearchParams;
+}) {
+  const locale = await resolvePublicContentLocale(searchParams);
+  return <SourcesIndexPageView locale={locale} />;
 }

frontend/components/landing/InstitutionalLandingPage.tsx

@@ -7,6 +7,7 @@ import {
 } from "@/components/landing/LandingAuthActions";
 import {
   LANDING_LOCALE_COOKIE,
+  landingLocaleHref,
   pickLandingLocale,
   type LandingLocale,
 } from "@/components/landing/landingLocale";
@@ -324,7 +325,7 @@ function InstitutionalLandingScreen({ locale }: { locale: LandingLocale }) {
             <Link href="/docs/chart-guide" className="hover:text-slate-950">
               {isEn ? "Guide" : "读图"}
             </Link>
-            <Link href="/briefs" className="hover:text-slate-950">
+            <Link href={landingLocaleHref("/briefs", locale)} className="hover:text-slate-950">
               {isEn ? "Briefs" : "简报"}
             </Link>
             <a href="#pricing" className="hover:text-slate-950">

frontend/components/landing/__tests__/landingPricingReferral.test.ts

@@ -104,7 +104,11 @@ export function runTests() {
     "landing supported cities must render names and station codes from the generated city groups",
   );
   assert(source.includes("#contact"), "landing navigation must expose the contact section");
-  assert(source.includes('href="/briefs"'), "landing navigation must expose public Weather Market Brief assets");
+  assert(
+    source.includes("landingLocaleHref") &&
+      source.includes('href={landingLocaleHref("/briefs", locale)}'),
+    "landing navigation must expose public Weather Market Brief assets while preserving the current locale",
+  );
   assert(source.includes('isEn ? "Briefs" : "简报"'), "landing page must label the public brief entry in both languages");
   assert(source.includes('id="contact"'), "landing page must include a contact section");
   assert(source.includes("yhrsc30@gmail.com"), "landing page must show the operator contact email");

frontend/components/landing/landingLocale.ts

@@ -38,3 +38,10 @@ export function pickLandingLocale(
 export function nextLandingLocale(locale: LandingLocale): LandingLocale {
   return locale === "zh-CN" ? "en-US" : "zh-CN";
 }
+
+export function landingLocaleHref(pathname: string, locale: LandingLocale): string {
+  const [pathWithQuery, hash] = pathname.split("#", 2);
+  const separator = pathWithQuery.includes("?") ? "&" : "?";
+  const localizedPath = `${pathWithQuery}${separator}${LANDING_LOCALE_QUERY_PARAM}=${encodeURIComponent(locale)}`;
+  return hash ? `${localizedPath}#${hash}` : localizedPath;
+}

frontend/components/public-content/PublicContentPages.tsx

@@ -1,6 +1,6 @@
 import Link from "next/link";
 import { LandingLocaleToggle } from "@/components/landing/LandingLocaleToggle";
-import type { LandingLocale } from "@/components/landing/landingLocale";
+import { landingLocaleHref, type LandingLocale } from "@/components/landing/landingLocale";
 import {
   METHODOLOGY_PAGES,
   PUBLIC_CONTENT_COPY,
@@ -44,21 +44,21 @@ function PublicHeader({ locale = "en-US" }: { locale?: LandingLocale }) {
   return (
     <header className="border-b border-slate-200 bg-white/90">
       <div className="mx-auto flex w-full max-w-6xl flex-col gap-3 px-4 py-4 sm:flex-row sm:items-center sm:justify-between sm:px-6 lg:px-8">
-        <Link className="text-base font-black text-slate-950" href="/">
+        <Link className="text-base font-black text-slate-950" href={landingLocaleHref("/", locale)}>
           PolyWeather
         </Link>
         <div className="flex flex-wrap items-center gap-2 sm:justify-end">
           <nav className="flex flex-wrap gap-2 text-sm font-semibold text-slate-700">
-            <Link className="rounded-md px-2.5 py-1.5 hover:bg-slate-100" href="/briefs">
+            <Link className="rounded-md px-2.5 py-1.5 hover:bg-slate-100" href={landingLocaleHref("/briefs", locale)}>
               {locale === "en-US" ? "Briefs" : "简报"}
             </Link>
-            <Link className="rounded-md px-2.5 py-1.5 hover:bg-slate-100" href="/methodology">
+            <Link className="rounded-md px-2.5 py-1.5 hover:bg-slate-100" href={landingLocaleHref("/methodology", locale)}>
               {copy.methodology}
             </Link>
-            <Link className="rounded-md px-2.5 py-1.5 hover:bg-slate-100" href="/sources">
+            <Link className="rounded-md px-2.5 py-1.5 hover:bg-slate-100" href={landingLocaleHref("/sources", locale)}>
               {copy.sources}
             </Link>
-            <Link className="rounded-md px-2.5 py-1.5 hover:bg-slate-100" href="/docs/intro">
+            <Link className="rounded-md px-2.5 py-1.5 hover:bg-slate-100" href={landingLocaleHref("/docs/intro", locale)}>
               {copy.docs}
             </Link>
           </nav>
@@ -103,7 +103,7 @@ function SourceLinks({ locale = "en-US", slugs }: { locale?: LandingLocale; slug
         return (
           <Link
             className="rounded-md border border-slate-200 bg-white px-3 py-1.5 text-xs font-semibold text-slate-700 hover:border-slate-300 hover:bg-slate-50"
-            href={sourcePath(localizedSource)}
+            href={landingLocaleHref(sourcePath(localizedSource), locale)}
             key={slug}
           >
             {localizedSource.title}
@@ -124,7 +124,7 @@ function MethodologyLinks({ locale = "en-US", slugs }: { locale?: LandingLocale;
         return (
           <Link
             className="rounded-md border border-slate-200 bg-white px-3 py-1.5 text-xs font-semibold text-slate-700 hover:border-slate-300 hover:bg-slate-50"
-            href={methodologyPath(localizedPage)}
+            href={landingLocaleHref(methodologyPath(localizedPage), locale)}
             key={slug}
           >
             {localizedPage.title}
@@ -152,7 +152,7 @@ function BriefCard({
             {brief.cityName} / {brief.date}
           </p>
           <h2 className="mt-2 text-xl font-black text-slate-950">
-            <Link href={briefPath(brief)}>{brief.title}</Link>
+            <Link href={landingLocaleHref(briefPath(brief), locale)}>{brief.title}</Link>
           </h2>
         </div>
         <span className="rounded-md bg-emerald-50 px-2.5 py-1 text-xs font-bold text-emerald-800">
@@ -170,7 +170,7 @@ function BriefCard({
         ))}
       </div>
       <div className="flex flex-wrap items-center gap-3">
-        <Link className={secondaryButton} href={briefPath(brief)}>
+        <Link className={secondaryButton} href={landingLocaleHref(briefPath(brief), locale)}>
           {readBriefLabel}
         </Link>
         <SourceLinks locale={locale} slugs={brief.sourceSlugs.slice(0, 2)} />
@@ -291,7 +291,7 @@ export function BriefDetailPageView({
               >
                 {localizedBrief.primaryCtaLabel}
               </PublicContentCta>
-              <Link className={secondaryButton} href="/briefs">
+              <Link className={secondaryButton} href={landingLocaleHref("/briefs", locale)}>
                 {copy.allPublicBriefs}
               </Link>
             </div>
@@ -315,7 +315,7 @@ export function BriefDetailPageView({
             <div className="mt-4">
               <PublicContentOutboundLink
                 className={secondaryButton}
-                href={`https://twitter.com/intent/tweet?text=${encodeURIComponent(localizedBrief.distributionText)}&url=${encodeURIComponent(absolutePublicUrl(briefPath(localizedBrief)))}`}
+                href={`https://twitter.com/intent/tweet?text=${encodeURIComponent(localizedBrief.distributionText)}&url=${encodeURIComponent(absolutePublicUrl(landingLocaleHref(briefPath(localizedBrief), locale)))}`}
                 payload={{ city: localizedBrief.city, date: localizedBrief.date, destination: "x_intent" }}
               >
                 {copy.shareOnX}
@@ -365,26 +365,33 @@ function InfoRow({ label, value }: { label: string; value: string }) {
   );
 }
 
-export function MethodologyIndexPageView() {
+export function MethodologyIndexPageView({
+  locale = "en-US",
+}: {
+  locale?: LandingLocale;
+} = {}) {
+  const copy = PUBLIC_CONTENT_COPY[locale];
+  const pages = METHODOLOGY_PAGES.map((page) => localizeMethodologyPage(page, locale));
+
   return (
     <div className={pageShell}>
-      <PublicHeader />
+      <PublicHeader locale={locale} />
       <PageIntro
-        description="Public methodology pages explain how PolyWeather handles DEB blending, settlement-source priority, freshness, and source reconciliation for prediction-market weather analysis."
-        eyebrow="Methodology"
-        title="How PolyWeather reads weather markets"
+        description={copy.methodologyIndexDescription}
+        eyebrow={copy.methodologyIndexEyebrow}
+        title={copy.methodologyIndexTitle}
       />
       <div className={contentWrap}>
         <section className="grid gap-4 md:grid-cols-2">
-          {METHODOLOGY_PAGES.map((page) => (
+          {pages.map((page) => (
             <article className={`${panel} p-5`} key={page.slug}>
-              <p className={sectionTitle}>{formatDate(page.updatedAt)}</p>
+              <p className={sectionTitle}>{formatDate(page.updatedAt, locale)}</p>
               <h2 className="mt-2 text-2xl font-black text-slate-950">
-                <Link href={methodologyPath(page)}>{page.title}</Link>
+                <Link href={landingLocaleHref(methodologyPath(page), locale)}>{page.title}</Link>
               </h2>
               <p className={`${bodyText} mt-3`}>{page.description}</p>
-              <Link className={`${secondaryButton} mt-5`} href={methodologyPath(page)}>
-                Read methodology
+              <Link className={`${secondaryButton} mt-5`} href={landingLocaleHref(methodologyPath(page), locale)}>
+                {copy.readMethodology}
               </Link>
             </article>
           ))}
@@ -394,7 +401,16 @@ export function MethodologyIndexPageView() {
   );
 }
 
-export function MethodologyDetailPageView({ page }: { page: MethodologyPage }) {
+export function MethodologyDetailPageView({
+  page,
+  locale = "en-US",
+}: {
+  page: MethodologyPage;
+  locale?: LandingLocale;
+}) {
+  const copy = PUBLIC_CONTENT_COPY[locale];
+  const localizedPage = localizeMethodologyPage(page, locale);
+
   return (
     <div className={pageShell}>
       <PublicContentAnalytics
@@ -402,13 +418,17 @@ export function MethodologyDetailPageView({ page }: { page: MethodologyPage }) {
         onceKey={`methodology:${page.slug}`}
         payload={{ slug: page.slug, content_type: "methodology" }}
       />
-      <PublicHeader />
-      <PageIntro description={page.description} eyebrow="Methodology" title={page.title} />
+      <PublicHeader locale={locale} />
+      <PageIntro
+        description={localizedPage.description}
+        eyebrow={copy.methodologyIndexEyebrow}
+        title={localizedPage.title}
+      />
       <div className={contentWrap}>
         <article className={`${panel} p-5`}>
-          <p className="max-w-3xl text-base leading-7 text-slate-700">{page.summary}</p>
+          <p className="max-w-3xl text-base leading-7 text-slate-700">{localizedPage.summary}</p>
           <div className="mt-8 grid gap-8">
-            {page.sections.map((section) => (
+            {localizedPage.sections.map((section) => (
               <section key={section.heading}>
                 <h2 className="text-xl font-black text-slate-950">{section.heading}</h2>
                 <p className={`${bodyText} mt-3`}>{section.body}</p>
@@ -428,26 +448,33 @@ export function MethodologyDetailPageView({ page }: { page: MethodologyPage }) {
   );
 }
 
-export function SourcesIndexPageView() {
+export function SourcesIndexPageView({
+  locale = "en-US",
+}: {
+  locale?: LandingLocale;
+} = {}) {
+  const copy = PUBLIC_CONTENT_COPY[locale];
+  const sources = SOURCE_PAGES.map((source) => localizeSourcePage(source, locale));
+
   return (
     <div className={pageShell}>
-      <PublicHeader />
+      <PublicHeader locale={locale} />
       <PageIntro
-        description="Source pages separate official observations, airport observations, and model guidance so readers can inspect why PolyWeather prioritizes settlement-relevant evidence."
-        eyebrow="Sources"
-        title="Weather source notes for public audit"
+        description={copy.sourceIndexDescription}
+        eyebrow={copy.sourceIndexEyebrow}
+        title={copy.sourceIndexTitle}
       />
       <div className={contentWrap}>
         <section className="grid gap-4 md:grid-cols-2">
-          {SOURCE_PAGES.map((source) => (
+          {sources.map((source) => (
             <article className={`${panel} p-5`} key={source.slug}>
               <p className={sectionTitle}>{source.operator}</p>
               <h2 className="mt-2 text-2xl font-black text-slate-950">
-                <Link href={sourcePath(source)}>{source.title}</Link>
+                <Link href={landingLocaleHref(sourcePath(source), locale)}>{source.title}</Link>
               </h2>
               <p className={`${bodyText} mt-3`}>{source.description}</p>
-              <Link className={`${secondaryButton} mt-5`} href={sourcePath(source)}>
-                Read source note
+              <Link className={`${secondaryButton} mt-5`} href={landingLocaleHref(sourcePath(source), locale)}>
+                {copy.readSourceNote}
               </Link>
             </article>
           ))}
@@ -457,32 +484,60 @@ export function SourcesIndexPageView() {
   );
 }
 
-export function SourceDetailPageView({ source }: { source: SourcePage }) {
+export function SourceDetailPageView({
+  source,
+  locale = "en-US",
+}: {
+  source: SourcePage;
+  locale?: LandingLocale;
+}) {
+  const localizedSource = localizeSourcePage(source, locale);
+  const labels =
+    locale === "en-US"
+      ? {
+          cadence: "Cadence",
+          coverage: "Coverage",
+          operator: "Operator",
+          reliability: "Reliability notes",
+          relatedMethodology: "Related methodology",
+          settlementUse: "Settlement use",
+          sourceNote: "Source note",
+        }
+      : {
+          cadence: "频率",
+          coverage: "覆盖范围",
+          operator: "运营方",
+          reliability: "可靠性备注",
+          relatedMethodology: "相关方法",
+          settlementUse: "结算用途",
+          sourceNote: "来源说明",
+        };
+
   return (
     <div className={pageShell}>
-      <PublicHeader />
-      <PageIntro description={source.description} eyebrow="Source note" title={source.title} />
+      <PublicHeader locale={locale} />
+      <PageIntro description={localizedSource.description} eyebrow={labels.sourceNote} title={localizedSource.title} />
       <div className={contentWrap}>
         <article className={`${panel} grid gap-6 p-5 lg:grid-cols-[0.9fr_1.4fr]`}>
           <dl className="grid gap-3 text-sm">
-            <InfoRow label="Operator" value={source.operator} />
-            <InfoRow label="Coverage" value={source.coverage} />
-            <InfoRow label="Cadence" value={source.cadence} />
-            <InfoRow label="Settlement use" value={source.settlementUse} />
+            <InfoRow label={labels.operator} value={localizedSource.operator} />
+            <InfoRow label={labels.coverage} value={localizedSource.coverage} />
+            <InfoRow label={labels.cadence} value={localizedSource.cadence} />
+            <InfoRow label={labels.settlementUse} value={localizedSource.settlementUse} />
           </dl>
           <div>
-            <p className={sectionTitle}>Reliability notes</p>
+            <p className={sectionTitle}>{labels.reliability}</p>
             <ul className="mt-4 grid gap-3">
-              {source.reliabilityNotes.map((note) => (
+              {localizedSource.reliabilityNotes.map((note) => (
                 <li className={bodyText} key={note}>
                   {note}
                 </li>
               ))}
             </ul>
             <div className="mt-6">
-              <p className={sectionTitle}>Related methodology</p>
+              <p className={sectionTitle}>{labels.relatedMethodology}</p>
               <div className="mt-4">
-                <MethodologyLinks slugs={source.relatedMethodologySlugs} />
+                <MethodologyLinks locale={locale} slugs={localizedSource.relatedMethodologySlugs} />
               </div>
             </div>
           </div>
@@ -499,8 +554,8 @@ function formatDateTime(value: string, locale: LandingLocale = "en-US") {
   }).format(new Date(value));
 }
 
-function formatDate(value: string) {
-  return new Intl.DateTimeFormat("en", {
+function formatDate(value: string, locale: LandingLocale = "en-US") {
+  return new Intl.DateTimeFormat(locale === "en-US" ? "en" : "zh-CN", {
     dateStyle: "medium",
   }).format(new Date(value));
 }

frontend/components/public-content/__tests__/publicContentAssets.test.ts

@@ -17,6 +17,7 @@ export function runTests() {
   const analyticsPath = path.join(root, "lib", "app-analytics.ts");
   const analyticsIslandPath = path.join(root, "components", "public-content", "PublicContentAnalytics.tsx");
   const publicPagesPath = path.join(root, "components", "public-content", "PublicContentPages.tsx");
+  const localeHelperPath = path.join(root, "components", "landing", "landingLocale.ts");
   const sitemapPath = path.join(root, "app", "sitemap.ts");
 
   for (const requiredPath of [
@@ -35,11 +36,14 @@ export function runTests() {
 
   const content = fs.readFileSync(contentPath, "utf8");
   const briefDetail = fs.readFileSync(briefDetailPath, "utf8");
+  const methodologyIndex = fs.readFileSync(methodologyIndexPath, "utf8");
   const methodologyDetail = fs.readFileSync(methodologyDetailPath, "utf8");
+  const sourcesIndex = fs.readFileSync(sourcesIndexPath, "utf8");
   const sourceDetail = fs.readFileSync(sourceDetailPath, "utf8");
   const analytics = fs.readFileSync(analyticsPath, "utf8");
   const analyticsIsland = fs.readFileSync(analyticsIslandPath, "utf8");
   const publicPages = fs.readFileSync(publicPagesPath, "utf8");
+  const localeHelper = fs.readFileSync(localeHelperPath, "utf8");
   const sitemap = fs.readFileSync(sitemapPath, "utf8");
   const briefsIndex = fs.readFileSync(briefsIndexPath, "utf8");
 
@@ -68,6 +72,13 @@ export function runTests() {
       content.includes("阅读简报"),
     "public brief content must provide Chinese and English localized copy",
   );
+  assert(
+    content.includes("METHODOLOGY_PAGE_LOCALIZATIONS") &&
+      content.includes("SOURCE_PAGE_LOCALIZATIONS") &&
+      content.includes("DEB 不是结算预言机") &&
+      content.includes("官方摘要可能滞后于原始点位观测"),
+    "public methodology and source pages must provide Chinese body-level localization, not title-only translation",
+  );
   assert(
     content.includes("24.5°C") &&
       content.includes("27.1°C") &&
@@ -104,6 +115,30 @@ export function runTests() {
       publicPages.includes('locale === "en-US" ? "Briefs" : "简报"'),
     "public content pages must render the shared language toggle and localized brief copy",
   );
+  assert(
+    localeHelper.includes("export function landingLocaleHref") &&
+      localeHelper.includes("LANDING_LOCALE_QUERY_PARAM"),
+    "landing locale helpers must expose a shared href builder for explicit locale navigation",
+  );
+  assert(
+    publicPages.includes("landingLocaleHref") &&
+      publicPages.includes('href={landingLocaleHref("/briefs", locale)}') &&
+      publicPages.includes("href={landingLocaleHref(briefPath(brief), locale)}") &&
+      publicPages.includes("href={landingLocaleHref(methodologyPath(localizedPage), locale)}") &&
+      publicPages.includes("href={landingLocaleHref(sourcePath(localizedSource), locale)}"),
+    "public content brief cards, nav, methodology, and source links must preserve the current locale",
+  );
+  assert(
+    methodologyIndex.includes("resolvePublicContentLocale(searchParams)") &&
+      methodologyIndex.includes("<MethodologyIndexPageView locale={locale} />") &&
+      methodologyDetail.includes("resolvePublicContentLocale(searchParams)") &&
+      methodologyDetail.includes("<MethodologyDetailPageView page={page} locale={locale} />") &&
+      sourcesIndex.includes("resolvePublicContentLocale(searchParams)") &&
+      sourcesIndex.includes("<SourcesIndexPageView locale={locale} />") &&
+      sourceDetail.includes("resolvePublicContentLocale(searchParams)") &&
+      sourceDetail.includes("<SourceDetailPageView source={source} locale={locale} />"),
+    "methodology and source public routes must resolve and pass the same locale as brief routes",
+  );
   assert(
     analytics.includes('"brief_view"') &&
       analytics.includes('"brief_cta_click"') &&

frontend/content/public-content.ts

@@ -661,17 +661,143 @@ const BRIEF_LOCALIZATIONS: Record<string, Partial<PublicBrief>> = {
   },
 };
 
-const METHODOLOGY_TITLE_LOCALIZATIONS: Record<string, string> = {
-  deb: "DEB 预测方法",
-  "settlement-sources": "结算源优先级",
+const METHODOLOGY_PAGE_LOCALIZATIONS: Record<string, Partial<MethodologyPage>> = {
+  deb: {
+    title: "DEB 预测方法",
+    description:
+      "PolyWeather 如何把 DEB 融合预报用于预测市场温度判断，同时不替代结算源证据。",
+    summary:
+      "DEB 是 PolyWeather 融合预报层的公开名称。它把模型指引、实时观测动量、来源新鲜度和站点上下文放在一起，帮助用户用更少单模型误判来判断最高温区间。",
+    sections: [
+      {
+        heading: "DEB 用来做什么",
+        body:
+          "DEB 不是结算预言机。它是决策辅助层，让实时观测路径和模型分歧更容易对比。",
+        bullets: [
+          "当模型指引与结算源证据冲突时，优先看结算源证据。",
+          "把过期或孤立的来源值视为需要质检的候选点。",
+          "展示预报区间以及区间变宽或收窄的原因。",
+        ],
+      },
+      {
+        heading: "关键输入",
+        body:
+          "融合层有用，是因为它组合了不同证据类别，而不是假设一次模型运行就足够。",
+        bullets: [
+          "最新官方或机场观测及其新鲜度。",
+          "ECMWF、GFS、ICON、GEM 以及可用本地来源之间的模型共识和分歧。",
+          "城市特定来源行为、站点选择和日内最高温时段。",
+        ],
+      },
+      {
+        heading: "如何复盘 DEB 偏差",
+        body:
+          "DEB 偏差应拆开来源新鲜度、模型分歧和结算源修订来复盘。",
+        bullets: [
+          "如果晚到来源 patch 改变了观测高温，将其归类为新鲜度或 replay 问题。",
+          "如果所有来源都新鲜但高温落在区间外，复盘模型权重和本地站点特征。",
+          "如果只有单一来源跳变，先审计相邻观测，再围绕异常点重训。",
+        ],
+      },
+    ],
+  },
+  "settlement-sources": {
+    title: "结算源优先级",
+    description:
+      "为什么 PolyWeather 先展示官方结算相关观测，而不是通用天气 API 数值。",
+    summary:
+      "预测市场用户关心的是合约最终结算数字。因此 PolyWeather 把官方站、机场和运营方特定来源行为放在泛消费者天气均值之上。",
+    sections: [
+      {
+        heading: "为什么通用天气值不够",
+        body:
+          "消费者天气应用经常平滑站点数据，或展示城市级近似值。市场结算可能依赖更窄的官方来源。",
+        bullets: [
+          "一个城市标签可能隐藏多个日高温不同的站点。",
+          "机场 METAR 可能比公开摘要更新更快，但未必是最终结算源。",
+          "官方来源修订往往比平滑的预报曲线更重要。",
+        ],
+      },
+      {
+        heading: "PolyWeather 展示什么",
+        body:
+          "终端会拆开来源标签、观测时间戳、预报模型和新鲜度状态，让用户审计数字形成路径。",
+        bullets: [
+          "图表中的结算源标签和站点上下文。",
+          "来源新鲜度、缓存策略和 SSE patch 可见性。",
+          "DEB 预报上下文与实时观测并列展示，而不是替代观测。",
+        ],
+      },
+    ],
+  },
 };
 
-const SOURCE_TITLE_LOCALIZATIONS: Record<string, string> = {
-  ecmwf: "ECMWF 模型指引",
-  hko: "HKO 官方观测",
-  metar: "METAR 机场观测",
-  mgm: "MGM 天气来源",
-  noaa: "NOAA 天气上下文",
+const SOURCE_PAGE_LOCALIZATIONS: Record<string, Partial<SourcePage>> = {
+  mgm: {
+    title: "MGM 天气来源",
+    description: "PolyWeather 针对土耳其 MGM 观测的来源说明，用于安卡拉类温度市场分析。",
+    operator: "土耳其国家气象局",
+    coverage: "土耳其官方站网络，包含安卡拉市场上下文。",
+    cadence: "来源频率会随站点和发布路径变化；终端仍需要检查新鲜度。",
+    settlementUse: "当安卡拉市场引用土耳其官方观测时，作为主要官方来源族使用。",
+    reliabilityNotes: [
+      "单点尖峰在接受前应与相邻时间戳比对。",
+      "官方摘要可能滞后于原始点位观测。",
+      "数值突然出现时，应检查缓存和 SSE replay 状态。",
+    ],
+  },
+  metar: {
+    title: "METAR 机场观测",
+    description: "PolyWeather 针对机场 METAR 观测的来源说明，用作温度市场工作流中的快速证据。",
+    operator: "机场天气观测网络",
+    coverage: "覆盖受支持市场的机场关联观测。",
+    cadence: "通常为小时级或更短，取决于机场和发布行为。",
+    settlementUse: "适合快速证据和机场关联合约；仍必须与合约的精确结算源校验。",
+    reliabilityNotes: [
+      "METAR 可能比官方日摘要更新更快。",
+      "机场暴露环境可能不同于市区官方站。",
+      "临近收盘的晚些 METAR 周期可能改变最高温判断。",
+    ],
+  },
+  ecmwf: {
+    title: "ECMWF 模型指引",
+    description: "PolyWeather 针对 ECMWF 模型指引的来源说明，它是 DEB 融合预报的一个输入。",
+    operator: "欧洲中期天气预报中心",
+    coverage: "全球数值天气预报指引。",
+    cadence: "模型运行频率取决于产品和摄取时间。",
+    settlementUse: "仅用于预报上下文，不替代实时官方观测的结算解释。",
+    reliabilityNotes: [
+      "模型偏暖或偏冷都应由实时观测验证。",
+      "当来源证据尚未稳定时，模型运行间变化可以提供参考。",
+      "模型分歧应与结算源数据并列展示，而不是凌驾其上。",
+    ],
+  },
+  hko: {
+    title: "HKO 官方观测",
+    description: "PolyWeather 针对香港天文台观测的来源说明，用于香港市场分析。",
+    operator: "香港天文台",
+    coverage: "香港官方观测网络和站点级上下文。",
+    cadence: "观测产品频率不同；终端仍应检查来源新鲜度。",
+    settlementUse: "作为香港站点和城市市场解释中的官方来源族使用。",
+    reliabilityNotes: [
+      "站点选择可能显著改变最高温读数。",
+      "机场观测应与更广泛的 HKO 网络读数分开解释。",
+      "湿度、风和午后短时日照会影响最终高温。",
+    ],
+  },
+  noaa: {
+    title: "NOAA 天气上下文",
+    description: "PolyWeather 针对 NOAA 上下文的来源说明，用于校验美国天气市场观测和摘要。",
+    operator: "美国国家海洋和大气管理局",
+    coverage: "美国官方天气观测、摘要和上下文产品。",
+    cadence: "频率取决于产品族和站点报告行为。",
+    settlementUse: "当合约规则引用 NOAA/NWS 数据时，用于审计和解释美国官方观测。",
+    reliabilityNotes: [
+      "官方摘要可能晚于快速机场观测到达。",
+      "日高温解释应匹配合约的站点和时区规则。",
+      "使用 NOAA 上下文确认机场观测是否具代表性。",
+    ],
+  },
 };
 
 export function localizeBrief(brief: PublicBrief, locale: LandingLocale): PublicBrief {
@@ -693,17 +819,22 @@ export function localizeBriefs(locale: LandingLocale) {
 
 export function localizeMethodologyPage(page: MethodologyPage, locale: LandingLocale): MethodologyPage {
   if (locale === "en-US") return page;
+  const localized = METHODOLOGY_PAGE_LOCALIZATIONS[page.slug] || {};
   return {
     ...page,
-    title: METHODOLOGY_TITLE_LOCALIZATIONS[page.slug] || page.title,
+    ...localized,
+    sections: localized.sections || page.sections,
   };
 }
 
 export function localizeSourcePage(page: SourcePage, locale: LandingLocale): SourcePage {
   if (locale === "en-US") return page;
+  const localized = SOURCE_PAGE_LOCALIZATIONS[page.slug] || {};
   return {
     ...page,
-    title: SOURCE_TITLE_LOCALIZATIONS[page.slug] || page.title,
+    ...localized,
+    reliabilityNotes: localized.reliabilityNotes || page.reliabilityNotes,
+    relatedMethodologySlugs: localized.relatedMethodologySlugs || page.relatedMethodologySlugs,
   };
 }